[BUGFIX] Fix undefined array key errors for PHP 8.0

Releases: master
Resolves: #95490
Change-Id: I8c7f055182e9a4da8ea5a7a4bd946cc69ce26e0f
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/71455


Tested-by: core-ci <typo3@b13.com>
Tested-by: Jochen <rothjochen@gmail.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Jochen <rothjochen@gmail.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>